Ink jet recording, a non-contact type recording system using water inks, has been rapidly spreading in recent years for various purposes, such as hard copy apparatuses for colored graphic data including Chinese characters due to the advantages thereof, for example, high printing speed, low noise level, ease of multi-color printing, high recording pattern flexibility, and the lack of a need for development or fixation.
Due to recent progress in high-speed printing and microprocessing, images obtained by ink jet printing are comparable in quality to images obtained by the conventional multi-color printing methods, such as offset printing. For a small number of copies, the ink jet printing is less expensive than the conventional plate making systems. Under these circumstances, attempts have been made to apply the ink jet printing to multi-color printing in addition to color photography recording. Moreover, attempts have been also made to replace dye inks having poor water resistance with pigment inks that have excellent water resistance and light resistance properties so as to enlarge the application range of ink jet printers to the formation of large-size posters and signboards for outdoor installation.
With the progress in ink jet printers, there is a corresponding requirement to improve the qualities of recording media.
For use in large-size posters and signboards for outdoor installation, for example, recording media should not only have high absorptivity of water inks, but also should have high water resistance to prevent the disappearance of prints even in bad weather and they should have high durability to resist tearing by strong wind.
To obtain high-grade prints from photographic output sources, such as printing photographs taken by digital cameras, recording media should have high glossiness and high water absorptivity.
As ink jet recording papers for the above-described purposes, there have been developed and marketed ink jet recording papers having highly gloss ink-receiving layer formed on pulp papers, plastic films or synthetic papers.
Although ink jet recording papers composed of a pulp paper substrate and high-gloss ink-receiving layer formed thereon for the above-described purposes have satisfactory glossiness and ink absorptivity, the substrate is susceptible to tearing. Thus, these ink jet recording papers suffer from a serious durability problem as a medium.
There have been frequent proposals to use plastic films or synthetic papers as highly durable substrates. In particular, a large number of plastic films having excellent glossiness and ink fixation properties have been proposed in which alumina compounds are used in the ink-receiving layer. For example, ink jet recording papers using an ink-receiving layer containing alumina, alumina hydrate and the like having excellent water absorptivity are disclosed in Japanese Patent Laid-Open No. 276670/1990, ibid. No. 215082/1991, ibid. No. 24335/1993, ibid. No. 218324/1994, ibid. No. 76161/1995, ibid. No. 34484/1999, ibid. No. 91236/1999, ibid. No. 91238/1999, ibid. No. 91242/1999, etc. In these cases, however, plastic films employed as the substrate have no water ink absorptivity, and as such it is necessary to provide an ink-receiving layer at a high coating dose. As a result, some problems arise; such as frequent cracking in the coating layer and repeated coating operations resulting in high costs.
To solve the above-described problems, the present inventors have found that a porous resin film having a liquid absorption capacity measured in accordance with “Japan TAPPI No. 51-87” of 0.5 ml/m2 or above has high durability and absorbs water-based liquids well, and a porous resin film having a surface contact angle of 110° or below can uniformly absorb an ink even at a high ink jet rate so that these porous resin films are appropriate for media in, for example, ink jet recording (Japanese Patent Application No. 320769/1999).
Although the above-described porous resin films have high ink absorptivity, they still suffer from some troubles, for example, they frequently show ink bleeding, have low water resistance against dye inks due to poor ink fixation properties, and give only less satisfactory appearance of prints due to low surface glossiness. That is to say, these films still need to be improved in ink bleeding, water resistance, and surface glossiness.
The present invention aims at providing less expensive ink jet recording papers having high glossiness and high durability and being capable of quickly absorbing inks without causing bleeding.